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NCEP Contributions to the WMO Severe Weather Forecasting Demonstration Project (SWFDP) and to the African Monsoon Multidisciplinary Analysis
(AMMA) Initiative
1. Rainfall, Heat Index and Dust Concentration Forecasts, (Issued on April 12, 2016)
1.1. Daily Rainfall and Maximum Heat Index Forecasts (valid: April 13 – April 17, 2016) The forecasts are expressed in terms of high probability of precipitation (POP) and high probability of maximum heat index, based on the NCEP/GFS, ECMWF and the NCEP Global Ensemble Forecasts System (GEFS) and expert assessment.
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Highlights
In the coming five days, there is an increased chance for two or more days of moderate to heavy rainfall over Western Ivory Coast, NW Nigeria, Cameroon, portions of Gabon, Congo, DRC, CAR, Uganda, Rwanda, Burundi, Kenya, Ethiopia and Tanzania
3 1.2. Atmospheric Dust Concentration Forecasts (valid: April 13 – April 15, 2016)
The forecasts are expressed in terms of high probability of dust concentration, based on the Navy Aerosol Analysis and Prediction System, NCEP/GFS lower-level wind forecasts and expert assessment.
Highlights
In the coming three days there is chance for moderate to high dust concentration over parts of Southern Algeria, Mali, Mauritania and Chad.
4 1.3. Model Discussion, Valid: April 13 – April 17, 2016
The central pressure value associated with the Azores high pressure system over Northeast Atlantic with an initial central pressure value of about 1036Hpa is expected to weaken to about 1019Hpa during the forecast period.
The St. Helena High pressure system over the Southeast Atlantic Ocean with an initial central pressure value of 1028Hpa is expected to weaken to 1022Hpa in the next 72Hrs. It is
expected to intensify to about 1032Hpa during the forecast period.
The Mascarene high pressure system over the Southwest Indian Ocean with an initial central value of 1029hPa is expected to weaken to 1028hPa in the next 72Hrs. It is expected to intensify to about 1032Hpa in the next 96Hrs.
At 925HPa level, dry northeasterly to easterly flow is expected to prevail across parts of the Sahel region and Northwest Africa, leading to increased atmospheric dust concentration in some of these areas.
At 850hPa level, moisture influx from Atlantic Ocean and its associated lower-level convergence is expected to prevail across coastal areas of West Africa, Gabon and Congo, resulting in enhanced rainfall activity in the area. A strong moisture convergence across southern DRC is expected to enhance rainfall during the forecast period. Monsoon flow from the Indian Ocean across East Africa and the seasonal wind convergences across eastern DRC and the Lake Victoria region is expected to enhance rainfall in the area during the forecast period.
In the coming five days, there is an increased chance for two or more days of moderate to heavy rainfall over Western Ivory Coast, NW Nigeria, Cameroon, portions of Gabon, Congo, DRC, CAR, Uganda, Rwanda, Burundi, Kenya, Ethiopia and Tanzania.
5 There is also an increased chance for maximum heat index values to exceed 40oC portions of Burkina Faso, Ivory Coast, Ghana, Togo, Benin, Nigeria, Niger, Chad, CAR and parts of South Sudan.
2.0. Previous and Current Day Weather over Africa
2.1. Weather assessment for the previous day (April 11, 2016)
Moderate to locally heavy rainfall was observed over portions of, Central Nigeria, Cameroon, Gabon, Congo, DRC, Uganda, Burundi, Kenya, Ethiopia, Northern Angola, Eastern Tanzania and Madagascar.
2.2. Weather assessment for the current day (April 12, 2016)
Intense convective clouds are observed across most parts of Ivory Coast, Ghana, CAR, Southern Sudan, Ethiopia, Uganda, DRC and Northern Angola.
Previous day rainfall condition over Africa (Left) based on the NCEP CPCE/RFE and current day cloud cover (right) based on IR Satellite image
Author: Asaniyan Bosede Rachael, (Nigerian Meteorological Agency) / CPC-African Desk); rachael.asaniyan@noaa.gov IR Satellite Image (valid 1530z April 12, 2016)
